Also known as Tan Spot, this disease is caused by the necrotrophic fungus Pyrenophora tritici-repentis. It is host-specific, affecting cereals, particularly wheat, although it can sometimes cause damage to other species, such as barley. It requires moisture to carry with infection, especially leaves that are extensively exposed to moisture. It’s fast spreading and can grow to epidemic situations, making it almost impossible to control in such proportions. Symptomatology can be similar to other diseases and issues, such as nutrient deficiencies, herbicide damage, stress, etc.
Yellow Spots on Leaves
Signs of damage
- Chlorosis. Leaves will turn yellow.
- Necrosis. Dead tissue, especially on leaves.
- Spotting. The appearance of groups of spots that can merge and create one large spot or harden into reddish-brown spots.
How to prevent
Good cultural practices should always be employed to guarantee higher resistance to plants. These practices include crop rotation, proper water practices, especially to avoid prolonged foliage exposure to moisture, good air circulation, and sanitizing tools and hands when handling multiple plants.
When possible, try choosing resistant varieties or similar alternative species. New plants should be isolated and kept in preventive quarantine until it is confirmed they’re not infected. Infected or damaged tissue should be removed and disposed of. Preventive fungicides can be used, as well as some natural alternatives, such as neem oil.
Heal
The first step is to ensure you’re dealing with Yellow Spots and not other issues with similar symptoms. This is crucial to assure plant recovery and can only be accessed by a pathologist.
There are some fungicides known to be effective against this issue. Search for active ingredients such as propiconazole or tebuconazole. These are not definitive solutions, as plants that are already dead can still allow for the production of spores, and reinfection can occur.
Plants that are too damaged should be removed to prevent further spread.
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